The present invention relates to an audio magnetic head mounted in video cassette recorders (VCRs) or audio tape decks, and particularly to a structure for mounting a head and an adjusting plate for mounting the head to a chassis.
Conventionally, an audio magnetic head is known to be disposed within a shielding case made of conductive metal wherein this shielding case is mounted to a chassis by means of an adjusting plate for azimuth adjustment to enable adjustments in height and angle of the head. While screws had been conventionally used for mounting the shielding case and the adjusting plate, in some cases threads were damaged at the time of screwing owing to a thin wall thickness of the shielding case that caused the threads to be shallow so that screwing could not be performed. It is further known to connect the shielding case and the adjusting plate through spot welding.
In order to solve the above-described problem of damages in the threads, as illustrated in FIG. 5, it has been devised to employ a tap plate 55 provided as a separate member for mounting the shielding case 54 to the adjusting plate 50. In this structure, the tap plate 55 formed with a tap that engages with a screw portion of a screw 51 is fixed to the shielding case 54, wherein the shielding case 54 is fixed by fastening the screw 51 upon inserting the screw 51 through hole portions 52, 53 formed on the adjusting plate 50 and the shielding case 54.
In another known arrangement for placing of a magnetic head to a mounting base, a projecting portion formed on the magnetic head is fitted into a groove formed on the mounting base whereupon both members are fitted and fixed (see, for instance, Japanese Unexamined Utility Model Publication No. SHO 63(1988)-6507 gazette, Japanese Unexamined Utility Model Publication No. Hei 1(1989)-93602 gazette and Japanese Utility Model Registration No. 2,555,512 gazette).
However, the above-described arrangement as illustrated in FIG. 5 is disadvantaged in that in addition to be necessary to form holes on the adjusting plate 50 and the shielding case 54 for inserting the screw 51 through, it is also necessary to form a tap on the tap plate 54, and the necessity of requiring the tap plate 55 and the screw 51 for fixing the adjusting plate 50 and the shielding case 54 resulted in an increased number of parts and assembling process and thus in higher manufacturing costs of the heads.
Moreover, since each magnetic head disclosed in the latter publications is an erasing head that does not require grounding, a case accumulating (i.e., accomodating) the head therein and a mounting base for such a case is a molded article made of plastics and in a complicated shape. In contrast thereto, an audio head requires grounding for shielding purposes so that it is necessary to form the shielding case and the mounting base of conductive metallic material that is difficult to be formed into a complicated shape when compared to one of a molded article made of plastics. This means that it is difficult to employ any of the structures that are disclosed in the referenced gazettes to an audio head. While mounting through spot welding would eliminate the necessity of providing a screw and a tap plate, it is difficult to accurately weld the magnetic head at an inclined angle since the magnetic head itself is in an elongated shape in height and an area of a surface to be spot welded is small.
The present invention has been made for solving the above-described conventional problems, and it is an object thereof to provide a structure for mounting an audio magnetic head to a chassis with which it is possible to fix the shielding case and the adjusting plate without using screws and to achieve low costs by decreasing the number of parts and assembling process.
For achieving the above objects, the present invention provides for a structure for mounting a head such that a head main body with an audio head for magnetic tapes is mounted to a chassis to be adjustable in height and angle, the structure comprising:
a shielding case made of conductive material for accumulating the head main body in its interior; and
an adjusting plate made of conductive material for supporting the shielding case with respect to the chassis to be adjustable in height and angle in an electrically conducted condition, wherein
conductive protrusions are formed on right and left side surfaces of the shielding case;
a pair of cut and raised pieces are formed on the adjusting plate through cutting and raising which oppose each other while leaving a clearance for pinching the shielding case between the pieces,
groove portions for engaging with the protrusions of the shielding case are formed on the cut and raised pieces; wherein
the shielding case is fixed to the adjusting plate by engaging the protrusions of the shielding case with the groove portions.
In the above arrangement, the shielding case accumulating therein the head main body may be mounted to the adjusting plate for adjusting the position of the head by engaging the conductive protrusions formed on the shielding case with the groove portions formed on the cut and raised pieces of the adjusting plate. With this arrangement, it will be no longer necessary to employ screws or tap plates as in the prior art, and it is thus possible to decrease manufacturing costs by decreasing the number of parts and mounting process.
In the above structure for mounting the head, one end of each groove portion of the cut and raised pieces is open and extends in a horizontal direction so that the shielding case and the adjusting plate may be electrically conducted by engaging the protrusions with the groove portions. With this arrangement, the protrusions and groove portions are allowed to contact in a planar manner, and it is possible to sufficiently secure conductivity and to ensure grounding of the shielding case.
In the above structure for mounting the head, the protrusions are formed in a round shape, and edges of the groove portions for engaging with the protrusions are formed as concave portions assuming arc-like shapes that fit along outer shapes of the protrusions at their interior end for positioning the protrusions. With this arrangement, the protrusions and the groove portions will contact in a planar manner so that it is possible to reliably perform grounding of the shielding case. Moreover, the positioned shielding case will not be shifted in position also upon receiving impact.
In the above structure for mounting the head, the groove portions are formed to be of a height with which the cut and raised pieces are flexed in the course of inserting the protrusions into the groove portions. In the above structure for mounting the head, an adhesive is filled into engaging portions between the groove portions and the protrusions. With this arrangement, the protrusions that are inserted in the groove portions may be reliably positioned and occurrence of positional shifts is eliminated.
In the above structure for mounting the head, the adjusting plate is supported to the chassis through adjusting screws at at least three dispersed points, each of which are adjustable in height, and is further urged upward through urging force of a compression spring inserted between the adjusting plate and the chassis.